Methods and systems of imaging cut stones

ABSTRACT

A method of imaging a cut stone. The method comprises a) identifying an orientation of a cut stone ( 202 ), b) creating a volumetric model of the cut stone according to the orientation ( 203 ), c) capturing a plurality of images of the cut stone from a plurality of viewing angles around the cut stone ( 204 ), d) cropping a plurality of segments depicting the cut stone from the plurality of images using the volumetric model ( 205 ), and e) generating a volumetric image of the cut stone from the plurality of segments ( 207,208 ).

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/255,920, filed on Sep. 12, 2011, which is a National Phase ofInternational Application No. PCT/US2010/000211, filed on Mar. 11, 2010,which claims priority of U.S. Provisional Patent Application No.61/202,537, filed on Mar. 11, 2009, the entirety of which are herebyincorporated by reference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to imagingand, more particularly, but not exclusively, to methods and systems ofimaging cut stones.

Cut stones, such as diamonds, are often analyzed based upon their visualappearance to the human eye. As such, a cut stone's visual appearance isa primary indicator of the quality of the diamond. Accordingly, becausediamond quality is substantially based on human visual perception,diamond analysis requires the exercise of judgment, the formation ofopinions and the ability to draw fine distinctions based on visualcomparisons.

With regard to diamond analysis, the foundation of diamond analysiscomprises analysis of the Four C's (color, clarity, cut and caratweight), a method of analysis defined by the Gemological Institute ofAmerica (GIA). Two of the Four C's, color and clarity, are evaluatedalong a scale or continuum. In the case of colorless to light-yellowcolored diamonds, an analysis is made along what is commonly referred toas the GIA D to Z scale. The GIA D to Z color scale, ranging fromcolorless to yellow, is an international standard which has beencalibrated to GIA's master diamonds since its development.

Usually, diamond quality analysis is performed by a team of trainedindividuals who visually inspect a diamond for features such asinclusions and structural flaws. This time-intensive process involvesnumerous inspections, measurements and checks by each individual. Theprocess also involves quality control and may include a variety ofnon-destructive tests to identify treatments, fillings or other defectsthat may affect the quality of a specimen.

During the last years methods which involve cut stone imaging have beendeveloped. For example, U.S. Pat. No. 7,461,017, filed on Apr. 30, 2004describes system and method of providing informational certificatesconcerning characteristics of jewelry items to customers. The systemincludes a terminal having a user interface configured to receive userinput information concerning at least a first characteristic of a firstjewelry item, a camera device capable of obtaining image informationregarding at least a part of the first jewelry item, and a printingdevice at least temporarily coupled to the terminal and the cameradevice and capable of printing a first certificate, where the firstcertificate includes a first portion of information based upon the userinput information and a second portion of information based upon theimage information, and where the terminal, the camera device and theprinting device are proximate a local point of sale of the first jewelryitem.

Other methods and systems have been developed to improve or facilitatethe diamond evaluation process, for example U.S. Pat. No. 7,136,154filed on Jun. 9, 2003 describes a gemstone rating system which is usedfor rating the cut of diamonds in which particular cuts and features aremeasured and the results compared with and provided with a predeterminedscore depending upon deviations from a theoretical perfect cut; andwherein the deviation scores are summed and then subtracted from aninitially perfect score to provide a universally comparable indicationof quality of cut.

SUMMARY OF THE INVENTION

According to some embodiments of the present invention, there isprovided a method of imaging a cut stone. The method comprises a)identifying an orientation of a cut stone, b) creating a volumetricmodel of the cut stone according to the orientation, c) capturing aplurality of images of the cut stone from a plurality of viewing anglesaround the cut stone, d) cropping a plurality of segments depicting thecut stone from the plurality of images using the volumetric model, ande) generating a volumetric image of the cut stone from the plurality ofsegments.

Optionally, the method further comprises presenting the volumetric imageto allow imaging the cut stone from any of the plurality of viewingangles.

Optionally, the plurality of segments depicting the cut stone in a firstplacement, further comprising reposition the cut stone in a secondplacement and repeating the b)-d) to create a plurality of additionalsegments depicting the cut stone in the second placement, the generatingcomprising merging between the plurality of segments and the pluralityof additional segments to generate the volumetric image.

More optionally, the generating comprises correlating between theplurality of segments and the plurality of additional segments.

Optionally, the identifying comprises capturing a plurality ofcalibration images of the cut stone from a plurality of point of viewaround the cut stone and estimating the orientation according to ananalysis of the plurality of calibration images.

Optionally, the creating comprises capturing a plurality of modelingimages of the cut stone from a plurality of point of view around the cutstone and creating the volumetric model according to an analysis of theplurality of modeling images.

More optionally, the identifying comprises calculating a scanning pathaccording to the orientation and maneuvering at least one image sensorto capture the plurality of modeling images according to the scanningpath.

Optionally, the capturing is performed by maneuvering at least one imagesensor to capture the plurality of images according to at least one ofthe volumetric model and the orientation.

Optionally, the capturing comprises capturing the plurality of imagesfrom a plurality of viewing angles on a surface of a virtual spherearound the cut stone.

Optionally, the method further comprises illuminating the cut stone withlight diffused from a plurality of reflecting elements.

According to some embodiments of the present invention, there isprovided a system of imaging a cut stone. The system comprises a holderfor mounting a cut stone, at least one image sensor, an image sensoractuator which maneuvers the at least one image sensor to capture aplurality of images of the cut stone from a plurality of viewing anglesaround the cut stone, an image capturing module which analyses theplurality of images to compute a volumetric model of the cut stone andcrops a plurality of segments depicting the cut stone from a group ofthe plurality of images according to the volumetric model, areconstruction module which reconstructs a volumetric image of the cutstone from the plurality of segments, and an output unit which outputsthe volumetric image to allow imaging the cut stone from any of theplurality of viewing angles.

Optionally, the image capturing module which analyses the plurality ofimages to compute an orientation of the cut stone to compute a scanningpattern, further comprising a controller which instructs the holder andthe image sensor actuator to respectively rotate the cut stone and theimage sensor according to the scanning pattern when computing thevolumetric model.

More optionally, the system further comprises a controller whichinstructs the holder and the image sensor actuator to respectivelyrotate the cut stone and the image sensor to capture the group from theplurality of viewing angles.

Optionally, the viewing angles are on a surface of a virtual spherearound the cut stone.

Optionally, the holder is set for rotating the cut stone around a firstrotation axis, the image sensor actuator being configured for rotatingthe image sensor around a second rotation axis, the first and secondrotation axes are perpendicular to one another, the rotating beingperformed to maneuver the at least image sensor among the plurality ofviewing angles.

Optionally, the system comprises a background element set to maneuver sothat each image depicts the cut stone with the background element at theback.

Optionally, the system comprises a lighting setup which illuminates thecut stone and a light diffuser which is sized and shaped for beingplaced between the cut stone and the at least one image sensor, thelight diffuser having at least one slit for allowing the at least oneimage sensor to capture the plurality of images from the plurality ofviewing angles.

Optionally, the system comprises at least one illumination source placedin the light diffuser to increase the exposure of the at least one imagesensor.

Optionally, the system comprises a vacuum pressure generator formaintaining the cut stone on the holder.

Optionally, the system comprises an illumination source set to bemaneuvered with the at least image sensor so as to illuminate the cutstone from the plurality of viewing angles.

According to some embodiments of the present invention, there isprovided a method of imaging a cut stone. The method comprises a)generating a first partial volumetric image of a first part of a cutstone from a plurality of images taken from a plurality of viewingangles around the first part, b) generating a second partial volumetricimage of a second part of the cut stone from a plurality of additionalimages taken from a plurality of additional viewing angles around thesecond part, c) merging the first and second partial volumetric imagesto generate a volumetric image of the cut stone, and d) outputting thevolumetric image.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system. In anexemplary embodiment of the invention, one or more tasks according toexemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions. Optionally, the data processorincludes a volatile memory for storing instructions and/or data and/or anon-volatile storage, for example, a magnetic hard-disk and/or removablemedia, for storing instructions and/or data. Optionally, a networkconnection is provided as well. A display and/or a user input devicesuch as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a schematic illustration of a cut stone imaging system forgenerating a volumetric image of a cut stone, according to someembodiments of the present invention;

FIG. 2 is a schematic illustration of an image sensor actuator set tomaneuver an image sensor around a cut stone in a plane which is parallelto a rotation axis of a holder on which the cut stone is mounted,according to some embodiments of the present invention;

FIG. 3 is an exemplary schematic illustration of an exemplary cut stonefor depicting terms used herein;

FIG. 4 is a schematic illustration of a light setup having a set oflamps which are used to illuminate the cut stone on the holder,according to some embodiments of the present invention;

FIG. 5 is a flowchart of a method of imaging a cut stone, according tosome embodiments of the present invention;

FIGS. 6A and 6B are schematic illustrations of an exemplary holdersupporting exemplary cut stone in two different placements, according tosome embodiments of the present invention;

FIG. 7 is a flowchart of calculating the orientation of the cut stone inrelation to a coordinate system, according to some embodiments of thepresent invention;

FIG. 8 is a schematic illustration of the cut stone on a holder inrelation to the exemplary coordinate system, according to someembodiments of the present invention;

FIG. 9 is a flowchart of a method of generating a volumetric model basedon a plurality of circumferential images, according to some embodimentsof the present invention;

FIG. 10 is schematic illustration of external vertical angles of the cutstone, according to some embodiments of the present invention;

FIG. 11 is a flowchart of a cropping process in which a segmentdepicting the cut stone is identified and cropped, according to someembodiments of the present invention;

FIG. 12 is a flattened image of a cut stone segment taken from a rotatedmodel thereof, according to some embodiments of the present invention;

FIG. 13 is a binary mask of a cut stone segment, according to someembodiments of the present invention;

FIG. 14 is a includes a merged and correlated segment taken from avolumetric image of the cut stone;

FIG. 15 depicts an exemplary merge mask gradient, according to someembodiments of the present invention; and

FIG. 16 depicts an exemplary image taken from an exemplary mergedvolumetric image, according to some embodiments of the presentinvention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to imagingand, more particularly, but not exclusively, to methods and systems ofimaging cut stones.

According to some embodiments of the present invention, there isprovided a method and a system of automatically or semi automaticallygenerating a volumetric image of a cut stone, such as a diamond, thatallows a viewer to view the imaged cut stone from a plurality ofdifferent viewing angles. For example, the volumetric image images thecut stone from between about 60 and about 360 possible viewing angles,for example 144, in between about 5 and 180 different planes passingthrough the cut stone and having about 1° separating between them.

The system includes a holder, optionally rotating, for mounting a cutstone and one or more image sensors which are mounted on one or moreimage sensor actuators. The image sensor actuator maneuvers the imagesensor to capture a plurality of images of the cut stone from aplurality of viewing angles around the cut stone. Optionally, the imagesensor and the holder have perpendicular rotation axes. The systemfurther includes an image capturing module which analyses the pluralityof images to compute a volumetric model of the cut stone and crops aplurality of segments depicting the cut stone from a group of the imagesaccording to the volumetric model. The system further includes areconstruction module which reconstructs a volumetric image of the cutstone from the plurality of segments and an output unit which outputsthe volumetric image to allow imaging the cut stone from any of aplurality of viewing angles.

According to some embodiments of the present invention there is provideda method of imaging a cut stone. The method includes identifying anorientation of a cut stone, for example by analyzing a set ofcalibration images taken from a plurality of circumferential pointsaround the cut stone. Then, a volumetric model of the cut stone iscreated using the orientation, for example by acquiring and analyzing aplurality of modeling images captured along a scan path calculatedaccording to the orientation. Now, images of the cut stone are capturedfrom a plurality of viewing angles around the cut stone, for examplefrom a plurality of viewing angles on a virtual sphere surrounding thecut stone. Now, segments depicting the cut stone are cropped from theimages using the volumetric model. This process allows generating avolumetric image of the cut stone from the plurality of segments.

According to some embodiments of the present invention there is provideda method of imaging a cut stone using partial volumetric images. Themethod is based on a first partial volumetric image of a first part of acut stone generated from a plurality of images taken from a plurality ofviewing angles around the first part and a second partial volumetricimage of a second part of the cut stone generated from a plurality ofadditional images taken from a plurality of additional viewing anglesaround the second part. These images are optionally taken using thesystem outlined above and described below. This allows merging the firstand second partial volumetric images to generate a volumetric image ofthe cut stone and outputting the volumetric image, for example fordisplay.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

Reference is now made to FIG. 1, which is a schematic illustration of acut stone imaging system 100 of generating a volumetric image of a cutstone, according to some embodiments of the present invention. As usedherein, a volumetric image means a dataset that provides a multidimensional representation of the cut stone, for example a threedimensional representation. The volumetric image may be a set of aplurality of images, each depicting the cut stone from a differentviewing angle and/or a 3D element which is generated based on theplurality of images.

As used herein, a cut stone 99 means a cut and optionally polished pieceof mineral, such as a diamond, gemstone and the like. The cut may be,for example round brilliant cut, mixed cut, rose cut, and/or step cut.The cuts may be as defined in the following standards: accredited gemappraisers (AGA), American Standard, practical fine cut, Scandinavianstandard, Eulitz brilliant, ideal brilliant, and parker brilliant. Thisstandard is incorporated herein by reference.

The cut stone imaging system 100 includes a holder 101, optionallyrotating, for mounting a cut stone 99 and one or more image sensors 102,such as camera, for brevity referred to herein as an image sensor 102,which captures images of the cut stone 99. The image sensor 102 isconnected to an image sensor actuator 103 which maneuvers it to captureimages of the cut stone 99 from a plurality of point of view around theholder. Optionally, the image sensor actuator 103 is a lever actuated bya motor, such as a step motor. Optionally, the image sensor actuator 103supports the image sensor 102 so that its lens is at a distance of about10 centimeters from the cut stone during the rotation. Optionally, asshown at FIG. 2 the image sensor actuator 103 is set to maneuver theimage sensor 102 around the cut stone 99 in a plane parallel to therotation axis of the holder 101. In such an embodiment, the rotationaxis about which the image sensor 102 rotates is perpendicular to therotation axis about which the cut stone 99 rotates. This rotation axismaintains the image sensor approximately in front of the center of thestone. These rotation axes allow imaging the cut stone 99 from any pointon the surface of a virtual sphere around the cut stone 99. In order toimage segments which are concealed by the holder, the cut stone 99 isimaged in two opposing placements, for example as described below anddepicted in FIGS. 6A and 6B. The image sensor may be a charge coupleddevice (CCD) based sensor, a complementary metal oxide semiconductor(CMOS) based sensor and/or any other sensor for capturing an image of acut stone. Optionally, the image sensor 102 is 3 mega pixel MP sensor ormore. Optionally, the image sensor 102 has a replaceable lens. In such amanner, various lenses, for example macro lens 16 mm, 25 mm, 30 mm,and/or 50 mm may be selected and used based on the size of the cut stone99. Optionally, the image sensor 102 has a controllable focus,optionally determined according to the distance of the image sensor 102from gemstone. The distance may be manually set, extracted from thevolumetric model generated below, and/or estimated using a distancedetector, such as a laser based distance detector. Optionally, variousfocus depths are used for the same area, for example for imaging thetable. The focus may be changed by a focus motor inside the lens of theimage sensor 102, changing the location of the image sensor, and/orlifting the gemstone during the scan, for example using an elevatingelement in the holder 101. Optionally, the image sensor 102 includes amicroscope image sensor which allows capturing images for minorinclusions detection.

FIG. 3 is an exemplary schematic illustration of an exemplary cut stone99 for depicting terms used herein. The girdle 81, the pavilion 83, thecrown 84, the upper table 85 and the culet 82 are depicted withrespective numerals. Optionally, the image sensor 101 includes anillumination source which is directed toward the area it images.Optionally, the image sensor 102 is placed behind a half transferablemirror and/or a white reflector to reduce reflection. Optionally, thelens of the image sensor 102 is provided with a white reflector.

The cut stone imaging system 100 further includes a computing unit 105,such as a personal computer, a laptop, a microprocessor and/or a digitalsignal processing (DSP) and controller 104 which controls the imagesensor actuator 103. The computing unit 105 optionally hosts an imagecapturing module 106 which calculates motion scanning patterns formaneuvering the image sensor 102 and/or rotating the holder 101 and areconstruction module 107 which reconstructs a volumetric image of thecut stone 99 by merging a plurality of cut stone images taken from aplurality of points of view by the image sensor 102 the cut stone 99and/or the image sensor 102 are maneuvered. As the volumetric image isbased on a plurality of images taken from a plurality of points of viewaround cut stone, it may allow a viewer to receive an image of the cutstone from every possible angle. As further described below, thevolumetric image may not include pixels with estimated values andtherefore provides genuine and reliable representation of the cut stone99. The volumetric image which is generated below may be based only onimages of the cut stone 99 and therefore does not require using externaldata sources, such as predefined models, estimated contours and thelike. As such, the volumetric image may be used to accurately evaluatethe cut stone.

Optionally, the system 100 includes a lighting setup of illuminating thecut stone 99 while it is imaged. This allows capturing images with clearview of the inclusions of the cut stone 99, while increasing thebrightness of the cut stone 99. Optionally, compact florescent lampsand/or LEDs are used to provide neutral and homogeneous light.

The homogeneousness of the light allows merging images taken fromdifferent point of view on a virtual sphere encircling the cut stone 99so as to form a volumetric image without or substantially withoutbrightness differences. For example, the lighting set allows similarlyilluminating both the pavilion conoid below the girdle 81 and thetruncated crown conoid above the girdle 81 while they are imaged. Forexample, reference is now made to FIG. 4, which is a schematicillustration of a set of lamps 131 which are used to illuminate the cutstone 99 on the holder 101, according to some embodiments of the presentinvention. For example, the set of lamps 131 includes 6 LP 28 W coolwhite light bulbs which are positioned in the box.

Optionally, a background element is placed on the holder 101, to providea background to the images captured by the image sensor 102. In such amanner, a background element, optionally black, rotates with the holderassures that the cut stone 99 is between the image sensor 102 andbackground element during the imaging process.

As depicted in FIG. 4, the rotating holder 101 is placed at the centerof a box, such as a 35×35×35 cm box, having inner walls covered withwhite surface. Optionally, the light setup includes a light diffuser,for example a 15 cm diameter white lusterless hemispherical orsubstantially hemispherical element. The hemispherical element ispositioned so that its inner space is turned toward the holder 101 andthe cut stone 99 and so that the cut stone 99 is positioned in front ofthe middle of the hemispherical element, for example 5 centimeter (cm)below the upper edge. Optionally, a vertical slot of about 2 cm wide isformed in the front side of the hemispherical element. Optionally, thedistance between the cut stone 99 and the hemispherical element is about110 mm. This vertical slot allows imaging the cut stone 99, for exampleby rotating the image sensor 102 so that its optical axis passes throughthe vertical slot. The vertical slot is optionally higher than the tipof the light bulbs so that no direct light gets into the hemisphere.

The light setup allows illuminating the cut stone 99 with light diffusedfrom a plurality of reflecting elements, such as the walls of the boxand/or the light diffuser. In such embodiments, light is optionallydiffused a number of times, for example twice, in order to gethomogeneous and soft illumination. For example a first diffusion is fromthe outer box 132 where the light is diffused evenly from the innerwalls and the second diffusion is from the hemisphere where the light isfocus towards the cut stone 99. The multiple diffusions induce a clearillumination of the internals parts of the cut stone 99. Such anillumination increases the sparkling of the facets of the cut stone 99and cancels the effect of a direct reflection from surfaces of the cutstone 99, for example from the upper table 85. A clear view of the lowerfacets from inner space of a cut stone 99, such as a diamond, is alsoachieved.

Optionally, one or more illumination sources, such as an array of 3×3big, white LEDs are positioned inside the hemisphere so as to illuminatethat the cut stone 99 from a front position in relation to the slit.Optionally, each illumination source includes LEDs which are coveredwith a roughly polished acrylic glass foil in order to blur the sharpedges of the LEDs. In use, during the scanning process, the illuminationsource is energized to overexpose the image sensor 102 so that the imagecaptures the outline of the cut stone, achieving harsh contrast betweenthe stone and it's surrounding.

Reference is also made to FIG. 5, which is a flowchart of a method 200of imaging a cut stone, according to some embodiments of the presentinvention.

First, as shown at 201 the cut stone 99 is mounted on the rotatingholder 101, in a first placement, such as 101. For example, the cutstone 99 is placed as shown in FIG. 6A or as shown in FIG. 6B. Thesefigures respectively depict first and second placements of the cut stone99 in the holder 101. The first and second placements are opposingplacements. For example, when the cut stone 99 is a brilliant cutdiamond, the first placement is position the cut stone 99 with the tableside up and the second placement is placing the cut stone 99 with thepavilion side up. The holder 101 optionally includes a supportingelement 71, optionally annular, which holds the cut stone 99 so that theculet 82 is turned downward and the central axis of the cut stone 99 isperpendicular to the base of the holder 101. The holder allows mountingthe cut stone 99 steady during the scanning process. Optionally, thesupporting element 71 is detachable and replaceable. In such anembodiment, a supporting element, from a set of a plurality ofsupporting elements is selected according to the shape and/or size ofthe cut stone 99. In such a manner, specific stone cut may have adjustedsupport, for example round, oval, and the like.

Optionally, a vacuum pressure generator is used for maintaining the cutstone 99 on the holder 101, for example while it rotates. The vacuumpressure generator optionally includes a tube for generating vacuumattachment pressure on the cut stone 99. The tube is placed along theholder 101 so that is tip faces the supporting element 71. The tube isoptionally a white straw made of glass or acrylic glass, coupled to amotor hollow shaft. The tune allows applying a vacuum pressure on thecut stone 99 during the scanning process. This pressure holds the cutstone 99 in place. Optionally, an adapter, optionally made of silicon,is attached to the tip of the tube so as to fit the surface of the cutstone 99. When the stone is up direction, the stone culet is covered bythe adapter. When the stone is positioned down, the table of the stoneis placed on the adapter.

As shown at 202, the orientation of cut stone in its current placementis detected. Reference is now made to FIG. 7, which is a flowchart ofcalculating the orientation of the cut stone 99 in relation to acoordinate system, according to some embodiments of the presentinvention. For brevity, reference is also made to FIG. 3, which is animage of an exemplary cut stone, a diamond with a brilliant cut, asdescribed above.

First, as shown at 300, a set of a plurality of calibration imagesdepicting the cut stone 99 from a plurality of point of views around itare captured and provided. Optionally, these images, referred to hereinas calibration images, are images taken when the optical axis of thecircumferential image sensor 102 is substantially perpendicular to thegirdle of the diamond 99. Optionally, the calibration images are takenaround the diamond 99. For example, 360 images, each taken from adifferent angle between 0° and 259° degrees around the central axis ofthe cut stone 99, may be taken. Optionally, the horizontal angledifference between viewing angles of different images is between about1° and about 6°, for example 2.5°. For clarity, a viewing angle means anangle of an axis originated from a point in and/or on the cut stone 99,optionally from the center of the cut stone 99. The angle may be inrelation to the horizon and/or to a plane passing through the cut stone99, optionally through the center of the cut stone 99. Now, theorientation of the cut stone 99 is calculated according to thecalibration images.

Blocks 301-304 are repeated per calibration image. As shown at 301, theleft and right edges 401, 402 of the girdle are found. Optionally, thecalibration image is processed using a high pass filter. Then, two subimages are cropped around coordinates of previously identified left andright edges 401, 402 in a previously captured calibration image wherethe left and right edges in the first are identified by following thecontour of the gemstone 99, optionally, from the highest point thereofin relation to the horizon. Each cropped image is filled using a convexhull algorithm. This allows marking the left or the right edges 401, 402in it as the average of the 5 horizontal pixels which are the mostdistant from the center of the diamond, optionally identified accordingto the location of the culet 82.

As shown at 302, as shown at 403, the distance between the left andright edges 401 is calculated. This distance may be referred to hereinas a girdle line length. As shown at 303, the width of the girdle 404 iscalculated. This width may be referred to herein as a girdle width. Asshown at 304, an angle 405 between a line that connects the left andright edges 401 and the pavilion 83 or the crown 84, depends on thepositioning of the cut stone 99, is performed.

The data collected for each calibration image each 302-304 is stored ina plurality of vectors. The left and right edges in each image thedistance between the left and right edges in each image is documented inan distance vector, the width of the girdle 402 in each image isdocumented in a girdle width vector, and the angle between a line thatconnects the left and right edges and the pavilion/crown in each imageis documented in an inclination vector or an angle vector. Optionally,the coordinates are determined with respect to the coordinates of thecircumferential image sensor 102 around the girdle 402. These vectorsprovide a mapping of perimeters of the cut stone 99 and allowcalculating the orientation of the cut stone 99.

The cut stone 99 is oriented in relation to a coordinate system assignedin a three dimensional space. As shown at 305, the tilt of the cut stone99 in relation to a horizontal plane of the coordinate system isestimated, for example by calculating the average angle between theaverage girdle line and the horizontal plane. Now, as shown at 306, thenormal vector of the cut stone 99 is calculated according to thevectors. This allows, as shown at 307, calculating the angle between aprojection of the normal vector on the horizontal plane and X axis ofthe coordinate system, referred to herein as phi (Φ) and, as shown at308, the angle between the normal vector and Z axis of the coordinatesystem, referred to herein as theta (Θ). Optionally, the phi and thetheta are calculated after the effect of the tilt is cancelled. Forclarity, an exemplary coordinate system phi (Φ) and theta (Θ) are markedin FIG. 8 which is a schematic illustration of the cut stone 99 on aholder 101 in relation to the exemplary coordinate system, according tosome embodiments of the present invention.

Now, as shown at 309, the tilt, theta and phi are used for calculatingthe orientation of the cut stone 99. In should be noted that theta isthe amplitude of the sine created by the angle between the left and theright edges in all the images and phi is the rotation angle of thestone, in which the angle between the girdle and the horizontal axis ismaximal (equal to the theta).

Reference is now made, one again, to FIG. 5. After the orientation ofthe cut stone 99 is calculated, a volumetric model of the cut stone inthe current placement is evaluated as shown at 203.

Reference is now made to FIG. 9, which is a flowchart of a method ofgenerating a volumetric model based on a plurality of circumferentialimages, according to some embodiments of the present invention.

First, as shown at 501, a scanning path is calculated according to theorientation estimated in 202. Optionally, the motion scanning path iscalculated by canceling the effect of the tilt and theta distortionswhich are calculated for each calibration image, as described above.

This allows, as shown at 502, maneuvering the image sensor 102 along themotion scanning path so that its optical axis is substantiallyperpendicular to the girdle of the cut stone 99. While the image sensor102 is maneuvered along the motion scanning paths, a second set ofimages is captured, referred to herein as modeling images. Segments fromthese images are merged to reconstruct a volumetric model of the cutstone 99, as further described below. In use, the image sensor actuator103 optionally changes the elevation and/or the angle of the imagesensor 102 in relation to the horizon so that the image sensor 102 facesthe girdle all along the motion scanning path. Optionally, the amplitudeof the motion in each circumferential point of view is calculatedaccording to the theta computed according to a calibration image takenfrom the same circumferential point of view. In such an embodiment, thecut stone 99 in the captured image is tilted in the captured image whilethe girdle is straight.

For each image the following is performed. First, as shown at 503,external vertical angles are extracted. For clarity, reference is nowalso made to FIG. 10, which is schematic illustration of externalvertical angles of the cut stone 99. Optionally, the external verticalangles are angles defined according to the view vision of the imagesensor 102 when the cut stone 99 is in the first and second placements.For example the external vertical angles include the vertical anglewhich below it the table portion of the cut stone 99 is not clearlyvisible when the table faces up is imaged, referred to herein as aMinCrop, the vertical angle which above it the culet is not clearlyvisible when the pavilion faces up and imaged, referred to herein as aMaxCrop. These angles allow merging between images which fully depictthe pavilion side of the diamond and images which fully depict the tableside of the diamond. The external vertical angles optionally include theexternal vertical angles of the left and right edges. It should be notedthat though pavilion and table are for describing the placements and/orsides of the cut stone 99, cut stone with different cut may be imagedusing the system 100 and method 200. In such embodiment, pavilion refersto the lower side and table refers to the upper side.

As shown at 504, a function of the movement of the cut stone 99 allowscalculating a center of rotation movement and a tilt angle of the cutstone 99. Now, as shown at, the part that depicts the cut stone in themodeling image is segmented or sliced. For example, the image is croppedaround the estimated center of rotation movement. Then, the image isfiltered, for example using a high-pass filter and/or according to acertain threshold. This allows identifying the boundaries of the cutstone slice depicting in the modeling image.

As shown at 506, the cut stone slice is aligned according to theestimated angle of the cut stone 99.

As shown at 507, the cut stone slices from all the modeling images maynow be arranged, for example according to an average diameter betweentwo slices images from opposing angles. As used herein, oppositesegments are images depicting the cut stone 99 from two opposing pointsof view so that the opposite segments are mirrored (except the distancefrom the image sensor 102). The images are arranged around the Z axis ofthe coordinate system, according to the rotation of the cut stone 99 inrelation to the image sensor 102 along the motion scanning path.

This allows, as shown at 508, creating a volumetric model of thevolumetric portion of cut stone 99 which is imaged in the currentplacement from all the cut stone slices. Optionally, the volumetricmodel is filled using a convex hull algorithm.

Optionally, the size of a cut stone segment 99 may be corrected by usingan opposite cut stone segment 99, 180 degrees therefrom, and scaling theaverage diameters of both cut stone segment.

Optionally, an edge filter and/or identification of the lines densitythrough “image close” morphological methods are used to refine thecropping.

Optionally, the an image of the cut stone 99 which is taken when theoptical axis is on or parallel to the central axis of the cut stone 99is used for creating the volumetric model and/or for leveling thesegments.

Reference is now made, one again, to FIG. 5. Now, as shown at 204, a setof cut stone images are captured from a plurality of points of viewalong the surface of a virtual sphere surrounding the cut stone 99.Optionally, the horizontal and/or vertical angle difference betweenviewing angles of different images is between about 1° and about 4°, forexample 1° horizontal angle difference and 3.6° vertical angledifference. Optionally, the cut stone images are taken between about−40° and about 90° in relation to a plane passing via the girdle.Optionally, the image sensor is maneuvered in a scanning pattern whichis calculated such that is has a sine behavior of the center rotationmovement along the X axis and superposition of sine (verAng)*Xamp andcosine(verAng)*Yamp in the Y movement when X amp is the X movementamplitude in a side set (verAng=0), and Yamp is the Y axis movement.

The images are captured by rotating the holder 101 and the image sensoractuator 103 so as to change the viewing angle of the image sensor 102with respect to the surface of the cut stone 99. In each image, theoptical axis of the image sensor 102 is directed to another point on thesurface of the cut stone 99. This allows creating a volumetric imagebased on the volumetric model of the cut stone 99 in the currentplacement. The cropping process separates the segment of the image thatdepicts the cut stone 99 from the holder 101 and the background.

As described above, the cut stone 99 is placed on the holder, forexample manually. Moreover, the scanning pattern of the image sensor 102may vary according to the orientation of the cut stone 99, for exampleas described above. As such, the distance between the cut stone 99 andthe image sensor 102 may but by fixed and/or known in advance. Thisdeviation may be corrected during the rotation of the holder 101 and/orthe image sensor, according to the estimated center of the rotationaxis. Optionally, the correction is made by normalization of the size ofthe segment according a ratio of the diameter of the segment by anopposed slice diameter located 180° around the rotation circle. Thisopposed slice diameter outlines the stone from the other side, but atthe same time has a similar contour.

Now, as shown at 205, the cut stone images of the cut stone in thecurrent placement are cropped according to the respective volumetricmodel created in 203.

Reference is now made to FIG. 11, which is a flowchart 600 of a croppingprocess in which a segment depicting the cut stone 99 in its currentplacement is identified and cropped in a cut stone image, according tosome embodiments of the present invention. This process is held in eachone of the cut stone images.

First, as shown at 603, the image is aligned according to an estimatedangle. The alignment is optionally performed according to the scanningpattern that is used for capturing the plurality of images.

Now, as shown at 604, a binary mask for the segment is created from thevolumetric model. The volumetric model is rotated to match thehorizontal and vertical angle of viewing point depicted in the currentcut stone image. Optionally, the origin location of the volumetric modelis set such that the vertical angle=0°. In order to use the model formask creation, it is rotated horizontally and vertically so that it fitsthe current image. The 3D rotated model is flattened to fit the 2Dimage, for example as shown in FIG. 12. The flattened model is thanconvhulled and filled. The result is a binary mask of the cut stone 99that allows removing segments depicting the background and the holder101, as shown at FIG. 13.

As shown at 605, the mask is used for crop the segment. Optionally, anew image is created by multiplying the segment by the binary mask.Optionally, artificial background is created by multiplying thebackground of the segment by (1-mask). The output of this process is animage depicting the cut stone 99 in the current placement without thebackground or the holder 101. Now, after all the cut stone images havebeen cropped, a plurality of cut stone segments of the cut stone in thecurrent placement 99 from different angles is received. Optionally,these cut stone segments are combined to create a partial volumetricimage of the cut stone 99 in its current placement. For example, thepartial volumetric image may depict the cut stone 99 in a table upplacement, as shown at FIG. 6A or the cut stone 99 in a pavilion upplacement, as shown at FIG. 6B.

Optionally, the characteristics of the cut stone 99 are used forseparating the cut stone 99 from the background, for example forcreating the mask. Optionally, characteristics of the stones aremanually provided, from example using a man machine interface (MMI),such as a keyboard which it connected to the system 100 and/orautomatically provided for example using an image processing if thecaptured images and/or a scale which is connected to the holder. Thecharacteristics may be the estimated light reflected from the stone, thelight reflection strength, the color of the size, and/or its size. Thisallows refining the filters used to create the mask and/or edgedetection process.

Now as shown at 206, the cut stone 99 is overturned so that the currentplacement thereof changes, for example from a table up placement to apavilion up placement or vice versa. Blocks 202-205 are repeated whenthe cut stone 99 is in the current placement, which is now anotherplacement. This allows creating two sets of cut stone segments, eacharranged as a partial volumetric image of the cut stone 99. The firstset depicts the cut stone 99, in a first placement, from a plurality ofviewing angles and the second set depicts the cut stone 99, in a secondplacement, from a plurality of viewing angles. The first and secondplacements are optionally the pavilion up and the table up placements.

Now, as shown at 207, the cut stone segments of the cut stone in thefirst and second placements are now correlated. In such a manner, thehorizontal and vertical angles of a certain cut stone segment in thepartial volumetric image depicting the cut stone in the table upposition, referred to herein as a table volumetric image, is correlatedwith a respective cut stone image having similar horizontal and verticalangles and taken from of the partial volumetric image depicting the cutstone in the pavilion position, referred to herein as a pavilionvolumetric image.

Optionally, the correlation is performed in a multistep process.Optionally, the volumetric model created for the pavilion volumetricimage and the volumetric model created for the table volumetric imageare used. For brevity, these models are referred to herein as pavilionvolumetric model and table volumetric model.

In every step of the correlation, the pavilion volumetric model isrotated by a fixed horizontal angle and unified with the tablevolumetric model. This rotation allows creating a unified volume of thetwo models. Correlation is achieved when the unified volume is minimaland the two models are coincided. First, the common parts from the tableand pavilion volumetric models are identified and optionally extracted.Now, the pavilion volumetric model is turned to fit the shape of thetable volumetric model. Then the pavilion volumetric model is rotated toin a delta horizontal angle. Unify table volumetric model with therotated pavilion volumetric model. Optionally, each one of the table andthe pavilion volumetric models is represented as a 3D point matrix.These matrixes are appended onto on another, for example by appendingthe 3D point matrix of the table volumetric model to the 3D point matrixof the rotated pavilion volumetric model. Optionally, the volume of theunified model is calculated for each optional correlation and theselected correlation is the correlation that has the minimal unifiedvolume.

Additionally or alternately, the area surface of optional correlationbetween segments of the pavilion volumetric image and segments of thetable volumetric image sliced images is used for detecting correlation.The data source for this correlation includes the cut stone segmentssets of both the pavilion and table volumetric images, for examplecreated as described above.

Now, a first segment of the set of segments of the pavilion volumetricimage is shifted to be correlated with the last segment of the set ofsegments of the table volumetric image and a sequential segment becomesfirst segment. During this shifting the segments of the table volumetricimage are not shifted. Now, each segment of the pavilion volumetricimage is unified with a respective segment of the corresponding tablevolumetric image and a unified surface is calculated. The sum of all theunified surfaces is calculated and the result of this process representsa unified volume of the two volumetric images. This process isiteratively repeated n times for a set having n cut stone segments. Thecorrelation is achieved when the unified volume is minimal, anindication that the two volumetric images coincide.

Additionally or alternately, the distance between the left and rightedges, the width of the girdle and an angle between a line that connectsthe left and right edges 401 and the pavilion or the crown diameter isused for detecting correlation. The data for this correlation isdistance, width, and/or angle vectors which are calculated above.

First, the best and second best correlation points between a distancevector of a segment of the pavilion volumetric image and a distancevector of a segment of the table volumetric image are found. The widthand angle vectors may be used to determine which of the two isindicative of a real correlation and the exact location thereof. Thisdefines the correlation and allows rotating the cut stone segmentsaccording to the correlation points. Optionally, the correlation iscorrected by a visual indication by an operator. Optionally, theoperator points at the approximate area and the precise point isdetermined by the best correlation in this area. Optionally, the bottomand/or up images are found using image registration techniques forfinding a suitable picture for the bottom part.

Now, as shown at 208, partial volumetric images are merged to form acomplete volumetric image of the cut stone 99. The volumetric image ofthe cut stone 99 includes a plurality of merged correlated segments, forexample as depicted in FIG. 14. During this process partial andcomplementary images are combined into a single complete image of thecut stone 99 that includes parts which are not imaged by only one of thepartial volumetric images. As described above, some parts of the cutstone 99 are covered during the scan. For example, the tip of the cutstone 99 may be placed in the holder 101, as shown in FIG. 3. By usingsegments from both the pavilion and table volumetric images, a fullcoverage of all the surface of the cut stone 99 is received. First, amerge mask which contains values in the range [0, 1] for defining themerge ratio of each pixel is created. The value of each pixel definesthe proportions of the merge, where pixel with the value 1 indicatesthat the pixel is acquired from one set, for example the up set, 0indicates that the pixel is acquired from another set, for example thedown set.

This allows generating a volumetric image from one of the partialvolumetric images and adding and/or replacing pixels from the otherpartial volumetric image according to a merge mask. Optionally, themerge mask is produced as follows:

First, a merge mask skeleton is created by initiate a merge mask with‘0’. The dimensions of the merge mask skeleton are set according to thecropped images. Then, a girdle surface is extracted from griddle linesdefined in one of the volumetric models. The girdle surface is marked inthe mask. Now, the space between the girdle surface and the upperboundaries of the mask is filled with ‘1’. Pixels of the area are takenfrom the up set image solely. The bottom of the merge area is located inthe pavilion model. This stage point represents the stage and should notappear in the result. The girdle line is duplicated from the girdle lineto the area of the cut stone 99 stage point, while its value isattenuated from 1 to 0 in order to have a gradient image.

Below the stage point, the mask remain zeroed, this area will be takenfrom the pavilion image solely, for example see FIG. 15.

The segments of the pavilion volumetric image are multiplied by themerge mask, pixel by pixel and the segments of the table volumetricimage are multiplied by 1−(merge mask). The result of the twomultiplications is summed pixel by pixel giving the merged image. FIG.16 depicts an image taken from the merged volumetric images.

Now, as shown at 209, the volumetric image may be presented to theviewer, allowing her to view the cut stone 99 from any of the pluralityof viewing angles from which the images depicting the cut stone segmentswhere taken. This allows using a pointing device, such as a mouse or atouch screen, to rotate the cut stone 99, changing the display fromdisplaying one viewing angle to another viewing angle. The cut stone 99may be presented on any client terminal, such as a personal computer, atablet, a cellular phone, a Smartphone, a laptop and the like.

The rotation instructions are translated to a change in the mergedsegment of the volumetric image which is currently displayed to theuser. The volumetric image may be provided as an independent file, a setof a plurality of files, each represents a different merged segment andthe like.

According to some embodiments of the present invention, the system 100is used to examine automatically other aspects of the cut stone 99. Forexample an image processing module may be added to evaluate color,fluorescence, and/or cut according to known methods. Optionally,proportion valuation is done by using frequency spreading of the stone'sshape, fitting the stone to it in different angles in order to evaluatethe symmetry. Optionally, scales are used to evaluate weight.

According to some embodiments of the present invention, the system 100is used to authenticate the cut stone 99. For example, thermalconductivity examination may be done and/or a specific gravityexamination by visual volume identification and/or weighing. The thermalconductivity examination may be done using adapted sensors known in theart.

According to some embodiments of the present invention, the system 100is also used to identify the cut stone 99. As described above, thevolumetric image depicts the gemstone 99 from a plurality of viewingangles and therefore includes unique visual data about it, for examplethe clarity and/or exact cuts and/or impurities thereof. This uniquedata may be analyzed to identify the cut stone 99. For example, thevolumetric image of a derivative thereof may be matched with a databaseof identified volumetric images and/or derivatives thereof. Theidentification process may combine other characteristic identification,such as weight.

It is expected that during the life of a patent maturing from thisapplication many relevant systems and methods will be developed and thescope of the term image processing, module, image sensor, light source,and computing unit is intended to include all such new technologies apriori.

As used herein the term “about” refers to ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”. This termencompasses the terms “consisting of” and “consisting essentially of”.

The phrase “consisting essentially of” means that the composition ormethod may include additional ingredients and/or steps, but only if theadditional ingredients and/or steps do not materially alter the basicand novel characteristics of the claimed composition or method.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

The word “exemplary” is used herein to mean “serving as an example,instance or illustration”. Any embodiment described as “exemplary” isnot necessarily to be construed as preferred or advantageous over otherembodiments and/or to exclude the incorporation of features from otherembodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the invention may include a plurality of “optional”features unless such features conflict.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. A method of imaging a cut stone having a girdle,comprising: a) obtaining, in a first placement of the cut stone, a firstvolumetric model of a first part of the cut stone, including the girdle,and taking a plurality of first images of the first part of the cutstone from a plurality of viewing directions, each defined by itshorizontal and vertical angles relative to a plane passing via thegirdle; (b) obtaining, in a second placement of the cut stone, a secondvolumetric model of a second part of the cut stone, including thegirdle, and taking a plurality of second images of the second part ofcut stone from a plurality of viewing direction, each defined by itshorizontal and vertical angles relative to said plane passing via thegirdle; (c) correlating the second images with the first images usingthe first and second volumetric models, based on the horizontal andvertical angles, to obtain correlated images of the first and secondparts of the cut stone, with a unified volume of the first volumetricmodel and the second volumetric model being minimal and the firstvolumetric model and the second volumetric model coinciding; (d)generating a volumetric image of the cut stone by merging segmentscropped from the correlated images of the first and second parts of thecut stone; and (e) outputting said volumetric image so as to allow aviewer to view the cut stone with its first and second parts as imagedfrom the plurality of viewing directions.
 2. The method according toclaim 1, wherein said first part of the cut stone includes the cutstone's table and girdle, and the second part includes the cut stone'spavilion and girdle.
 3. The method according to claim 1, wherein thestep (a) includes obtaining a plurality of first modeling images of thefirst part of the cut stone and using the modeling images for generatingthe first volumetric model of the first part of the cut stone; whereinthe step (b) includes obtaining a plurality of second modeling images ofthe second part of the cut stone and using the modeling images forgenerating the second volumetric model of the second part of the cutstone; and wherein the using in steps (a) and (b) of the first andsecond volumetric models is for calculating scanning patterns; andwherein the using of the scanning patterns is for maneuvering accordingto them at least one of a holder of the cut stone and at least one imagesensor for capturing, by the at least one image sensor, the first andthe second images of the first and second parts of the cut stone,respectively.
 4. The method according to claim 3, wherein themaneuvering is performed by rotating the cut stone around a firstrotation axis, and rotating the at least one image sensor around asecond rotation axis, being perpendicular to the first rotation axis. 5.The method according to claim 3, wherein the maneuvering is performed soas to allow imaging the cut stone from any point on a surface of avirtual sphere around the cut stone.
 6. The method according to claim 3,wherein the maneuvering is performed under such illumination of the cutstone that allows to avoid an effect of direct reflection of light fromsurfaces of the cut stone.
 7. The method according to claim 3, whereinthe same image sensor that is used for capturing modeling images for thecreation of the volumetric models is maneuvered for capturing the firstand the second images.
 8. A system of imaging a cut stone having agirdle, the system comprising: a holder for mounting the cut stone infirst and second placements; at least one image sensor; an image sensoractuator configured to maneuver the at least one image sensor forcapturing a plurality of first images of a first part of the cut stonein its first placement and a plurality of second images of a second partof the cut stone in its second placement; each of the first and secondparts of the cut stone, including its girdle, and the first and thesecond images of these parts being taken from a plurality of viewingdirections, each defined by a horizontal and a vertical angles relativeto a plane passing via the girdle; an image capturing module configuredto correlate the second images with the first images using a firstvolumetric model of the first part of the cut stone and a secondvolumetric model of the second part of the cut stone, based on thehorizontal and vertical angles, to obtain correlated images of the firstand second parts of the cut stone, with a unified volume of the firstvolumetric model and the second volumetric model being minimal and thefirst volumetric model and the second volumetric model coinciding, andto crop segments from the first and second images; a reconstructionmodule for generating a volumetric image of the cut stone by mergingsegments of the correlated images of the first and second parts of thecut stone; and an output unit which outputs said volumetric image toallow viewing the cut stone from a plurality of viewing angles.
 9. Thesystem according to claim 8, wherein the image capturing module isconfigured for using the first and second volumetric models of the cutstone created in its respective first and second placements, for thecorrelation between the first and second images having similarhorizontal and vertical angles relative to the plane passing via thegirdle.
 10. The system according claim 9, wherein the image capturingmodule is configured to compute the first volumetric model of the firstpart of the cut stone and the second volumetric module of the secondpart of the cut stone, and to use the volumetric models for computingfirst and second scanning patterns, and the system further comprises acontroller, which instructs the holder and the image sensor actuator torespectively maneuver the image sensor and rotate the cut stone in eachof the first and second placements according to the respective first andsecond scanning patterns.
 11. The system according to claim 8, whereinthe holder is configured for rotating the cut stone around a firstrotation axis, the image sensor actuator being configured for rotatingthe image sensor around a second rotation axis, the rotating of both theholder and the image sensor being configured to provide the viewingdirections during the maneuvering, which the viewing directions include,in one of the first and second placements, a direction facing the cutstone's table facet, and in the other of the first and secondplacements, a direction facing the cut stone's pavilion.